
/*
  https://www.jianshu.com/p/f4efaa6b8fe6

  https://dart.cn/guides/language/language-tour#adding-features-to-a-class-mixins
  Mixins
  Mixin 是一种在多个类层次结构中重用代码的方法。下面的是声明一个 Mixin 的做法

 */
mixin Piloted {
  int astronauts = 1;

  void describeCrew() {
    print('Number of astronauts: $astronauts');
  }
}